Worry is a way we pray for something we don't want. Many believe that worrying makes a difference, since most of what we worry about never manifests. Yet that's not proof that worrying works.
More helpful is to create contingency plans. As in, "if this, than that." In other words, "if this happens, then I'll do that." That's what training is for, whether it's an airline pilot prepared to handle landing gear that doesn't retract, to you being prepared for the possible questions that might arise when calling a patient after their first adjustment.